Extensible nonwoven fabric

Abstract

Extensible nonwoven fabrics having improved elongation, extensibility, abrasion resistance and toughness. In particular, embodiments of the invention are directed to extensible spunbond fabrics comprising a polymeric blend of a metallocene catalyzed polypropylene, polyethylene, and a third polymer component.

That which is claimed: 
     
       1. A nonwoven fabric comprising a plurality of fibers that are bonded together to form a coherent web, the fibers comprising a polymeric blend of a metallocene catalyzed polypropylene component, a polyethylene component, and a third polymer component that is at least partially miscible in the metallocene catalyzed polypropylene component and polyethylene component, wherein the nonwoven fabric exhibits a 20 to 30% increase in toughness in comparison to a similar nonwoven fabric comprising a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       2. The fabric of  claim 1 , wherein the third polymer component comprises a polypropylene copolymer or terpolymer. 
     
     
       3. The fabric of  claim 1 , wherein the plurality of fibers are point bonded to each other with a bonding pattern having a cross-direction rod shape. 
     
     
       4. The fabric of  claim 1 , wherein the bonds cover 8 to 15% of a surface are of the nonwoven fabric. 
     
     
       5. The fabric of  claim 1 , wherein the nonwoven fabric has been subject to a solid state deformation such that the fibers have become permanently elongated. 
     
     
       6. The fabric of  claim 1 , wherein the fibers are extensible and substantially inelastic. 
     
     
       7. The fabric of  claim 1 , wherein the fibers are multicomponent fibers having a sheath/core arrangement in which the sheath comprises polyethylene and the core comprises said polymeric blend. 
     
     
       8. The fabric of  claim 1 , wherein the fibers are monocomponent fibers. 
     
     
       9. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits one or more of
 a) an increase in machine direction elongation at 5 N is that is from about 5 to 40% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; 
 b) an increase in cross direction elongation at 5 N is that is from about 5 to 40% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; 
 c) an increase in machine direction elongation at 10 N is that is from about 20 to 80% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; or 
 d) an increase in cross direction elongation at 10 N is that is from about 20 to 80% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
 
     
     
       10. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits an increase in machine direction elongation at 5 N is that is from about 10 to 30% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       11. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits an increase in cross direction elongation at 5 N is that is from about 10 to 30% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       12. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits an increase in machine direction elongation at 10 N is that is from about 25 to 70% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       13. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits an increase in cross direction elongation at 10 N is that is from about 25 to 70% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       14. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric, and wherein the fabric exhibits
 a) an increase in machine direction elongation at 5 N is that is from about 10 to 25% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; 
 b) an increase in cross direction elongation at 5 N is that is from about 10 to 25% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; 
 c) an increase in machine direction elongation at 10 N is that is from about 30 to 70% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene; and 
 d) an increase in cross direction elongation at 10 N is that is from about 30 to 70% in comparison to the similar fabric having a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
 
     
     
       15. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric in which the fibers have been thermally bonded with a bond pattern having a cylindrical or rod shape, and wherein the fabric exhibits one or more of
 a) an increase in machine direction elongation at 5 N is that is from about 20 to 250% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; 
 b) an increase in cross direction elongation at 5 N is that is from about 40 to 300% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; 
 c) an increase in machine direction elongation at 10 N is that is from about 30 to 225% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; or 
 d) an increase in cross direction elongation at 10 N is that is from about 15 to 150% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern. 
 
     
     
       16. The fabric of  claim 15 , wherein the bonds cover from 8 to 12% of the fabric. 
     
     
       17. The fabric of  claim 1 , wherein the fabric comprises a spunbond fabric in which the fibers have been thermally bonded with a bond pattern having a cylindrical or rod shape, and wherein the fabric exhibits one or more of
 a) an increase in machine direction elongation at 5 N is that is from about 25 to 150% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; 
 b) an increase in cross direction elongation at 5 N is that is from about 75 to 100% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; 
 c) an increase in machine direction elongation at 10 N is that is from about 75 to 125% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern; or 
 d) an increase in cross direction elongation at 10 N is that is from about 25 to 70% in comparison to a similar fabric that has been thermally bonded with an oval shaped bond pattern. 
 
     
     
       18. The fabric of  claim 1 , wherein the fabric has an abrasion resistance from about 0.02 to 0.06 mg/cm 2  as measured by The Sutherland Ink Rub test method. 
     
     
       19. The fabric of  claim 1 , wherein the fabric has a 20 to 30% increase in toughness in comparison to a similar nonwoven fabric comprising a Ziegler-Natta catalyzed polypropylene in place of the metallocene catalyzed polypropylene. 
     
     
       20. The fabric of  claim 1 , wherein the fibers have a reverse bicomponent arrangement and in which the polymer blend is present in a sheath of the fiber, and a polymer having a lower melting temperature than said polymer blend defines a core of the fiber. 
     
     
       21. A composite sheet material having an SMS or SMMS construction in which the spunbond layer comprises the nonwoven fabric of  claim 1 . 
     
     
       22. An absorbent article comprising the fabric of  claim 1 . 
     
     
       23. The absorbent article of  claim 22 , wherein the article comprises a diaper. 
     
     
       24. An extensible nonwoven fabric comprising the nonwoven of  claim 1  having a root mean square peak tensile of about 10 N/5 cm or less and a root mean square peak elongation greater than 400% as measured in accordance with the High Speed Deformation Simulation at 800 mm/minute. 
     
     
       25. The fabric of  claim 24 , wherein the fabric has a root mean square peak tensile of about 5 to 10 N/5 cm, and a root mean square peak elongation from about 400% to 600%. 
     
     
       26. The fabric of  claim 24 , wherein the fabric has a root mean square peak tensile of about 6 to 9 N/5 cm, and a root mean square peak elongation from about 425 to 550% as measured in accordance with the High Speed Deformation Simulation at 800 mm/minute. 
     
     
       27. The fabric of  claim 24 , wherein the fabric comprises a plurality of fibers having a bicomponent sheath core arrangement in which a first polymer component in the sheath has a higher melting temperature than a second polymer component in the core of the fiber. 
     
     
       28. The fabric of  claim 27 , wherein the first polymer component comprises a polymeric blend of a metallocene catalyzed polypropylene component, a polyethylene component, and a third polymer component that is at least partially miscible in the metallocene catalyzed polypropylene component and the polyethylene component.